Park Highlights

USGS Geology

Natural Bridges

National Monument

Utah

Diagram of Formation of Natural Bridges

How Natural Bridges Form
The rock in the park is a sandstone initially formed by windblown sand. The deep, looping White and Armstrong Canyons and the three bridges within them can be traced to the relentless action of water against the crossbedded sandstone. The desert stream would occasionally scour its bed with a great load of water and sand, so that conditions for forming natural bridges were set. Kachina and Sipapu straddle streams with long winding curves. (Owachomo, now straddling no stream, was apparently cut by the action of two streams.) When a river forms a great looping meander, almost circling back on itself, it can create the thin rock wall in which natural bridges form. Raging flood waters scrape away at both sides of the thin wall. Eventually the river breaks through and takes the shorter course under its new bridge, abandoning the old looping meander. The river continues to wear down the rock, enlarging the hole by cutting itself deeper. A natural bridge is temporary. Blocks fall from its undersides and its surfaces weather wear, and weaken. The span of Owachomo, for example, the oldest bridge, has worn thin.

The natural bridges represent three states: old age, maturity, and youth.

Owachomo Bridge no longer suffers stream erosion, but erosion by rain, frost action, and sandblast. Now in its late phase, it could already have a fatal crack, or it could stand for centuries.

Sipapu Bridge suffers little or no stream erosion because its abutments now lie far from the streambed. A mature bridge, it is largest in both height and span . Sipapu can be hard to spot from the overlook on the canyon rim, despite its size.

Kachina Bridge, in its youthful state, looms huge and bulky. Floodwaters in White Canyon still work to enlarge it. A trail threads the canyon between Sipapu and Kachina bridges.

Discovering Three Scenic Treasures
History Prospector Cass Hite came across these perforated rock walls, called natural bridges, when he was exploring White Canyon from his Colorado River placer gold camp in 1883. In 1904 The National Geographic Magazine publicized the bridges, and on April 16, 1908 resident Theodore Roosevelt proclaimed the national monument. Natural Bridges National Monument is Utah's first National Park Service area.
In 1904 the bridges were known by different names. Owachomo, Sipapu, and Kachina had been named, respectively, Edwin, Augusta, and Caroline, after early explorers or their relatives. In 1909 President William Howard Taft enlarged the boundaries and affixed the Hopi Indian names. Although Navajos and Paiutes are known to have lived in the area historically, there is no known Navajo term for the bridges. The Paiutes did not name the bridges individually but called them "Ma-Vah-Talk-Tump", meaning "under the horse's belly". The Hopi names were chosen because of the similarity between Hopi structures and the Anasazi cliff dwellings found throughout the area.

Owachomo, meaning "rock mound", is named for the large rounded rock mass found on the northeastern abutment of the bridge.

Sipapu means "the place of emergence" in Hopi legends.

Rock art on the third bridge resembles symbols which are found on kachina dolls, thus the name Kachina or ghost dancer.

Natural History
Millions of years ago these sandstones were deposited and then, as part of the Colorado Plateau, were slowly uplifted. Erosional forces gradually created the canyons and landscapes seen today. Plant communities have varied over time as well. Pollen studies indicate that this area was once a spruce-fir forest. Gradual climatic changes altered the dominant plant type; however, small pockets of Douglas-fir trees are still seen on the cooler, moister north-facing cliffs near Sipapu Bridge.

Precipitation is infrequent, unpredictable, and at times dramatic - varying between long periods of drought and periods of relatively heavy precipitation. Plants and animals have adapted to this environment. Microbiotic soil, the black and lumpy crust throughout the area, retains moisture and stabilizes and adds nutrients to the soil. This allows other plant communities, such as the pinyon juniper forest, to develop and mature.

How Bridges and Arches Differ

Natural bridges are formed by the erosive action of running water,

Arches are formed by other erosional forces (such as wind).

Stream erosion is the primary force in the formation of natural bridges. Natural bridges are enlarged and shaped by the freeze/thaw and percolation actions of water, which are also the major erosive processes that form arches.

These ruins are very fragile. Do not enter the structures or walk on or near walls. Leave everything you find as it is.

Geologic Setting
In 1904, National Geographic referred to the ‘Colossal Bridges of Utah’, grabbing the public interest in the first decade of the 20th Century. Theodore Roosevelt established Natural Bridges as Utah’s first National Monument . . . read more

Geologic History
Natural Bridges National Monument, Utah’s first national monument, was established to protect three large natural bridges and ancient masonry structures constructed by ancestral Puebloan people. Unlike an arch, like those at Arches National Park, a natural bridge forms through the process of flowing water . . . read more

Geologic Features & Processes
The three bridges in Natural Bridges National Monument, Sipapu, Kachina, and Owachomo, are among the ten largest in the world, and they are all developed in the Lower Permian Cedar Mesa Sandstone. Hopi names were assigned to the bridges because modern-day Hopis are descendents of the people who occupied these remote canyons . . . read more

Full ReportGeologic Resource Evaluation Report – A detailed geologic report is available that provides an introduction to the geologic history of the park and its geologic formations, identifies geologic features and processes that are important to park ecosystems, describes key resource management challenges and possible solutions, and lists geologic research and monitoring needs.

The spectacular geology in our national parks provides the answers to many
questions about the Earth. The answers can be appreciated through plate tectonics,
an exciting way to understand the ongoing natural processes that sculpt our
landscape. Parks and Plates is a visual and scientific voyage of discovery!

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